The present invention relates to an electron beam producing arrangement for a cathode ray tube having a target electrode constructed like a fluorescent screen, comprising a vessel-shaped metallic control electrode with a wall thickness which is reduced in the region of an opening for the passage of the beam and comprising a cathode arranged inside the control electrode and in front of the opening for the passage of the beam.
Beam generators for cathode ray tubes, which comprise a cathode wire running perpendicular to the tube axis, are already known from German Auslegeschrift No. 12 79 215, the cathode wire being arranged inside a vessel-shaped control electrode below the opening in the control electrode for passage of the beam. With very small heat output, sufficiently large beam currents may be produced for the cathode with this type of beam generator, if the opening for passage of the beam and the spacing therein are chosen to be sufficiently small. For reasons of stability, the thickness of the material of the control grid must however have a certain thickness whereby the necessary magnitudes are influenced relatively unfavourably. In an earlier German Patent Applicaton No. 25 38 436, it has already been suggested to introduce a fairly large opening into the control electrode in a system for producing an electron beam and to cover this opening with a thin foil which carries the opening for passage of the beam.